低渗油田压裂控水用聚电解质复合溶液性能研究

将阴离子聚丙烯酰胺(HPAM)与阳离子聚合物(DP-1)应用溶液共混法,制备了低渗油田压裂控水用聚电解质复合溶液。研究了阴阳离子聚合物稳定共存的条件,评价了复合溶液的耐温抗盐性能、抗剪切耐冲刷性能以及控水性能。结果表明,在一定量外加盐(KCl)的作用下,阴阳离子聚合物可形成稳定的低粘度聚电解质复合溶液,且具有良好的耐温性和抗盐性;随剪切速率的增加,复合溶液粘度先降低后又有增加;在60℃下岩心流动实验中,盐水驱替100 PV时残余阻力系数为2.66,具有良好的耐冲刷性;水相渗透率降低90.53%,油相渗透率降低14.60%,具有明显的不等比例降低油水相渗透率特征,可用于近水或高含水低渗油层控水压裂改造,降低现场施工风险。

Performance of polyelectrolyte complex solution for water control in the hydraulic fracturing of low permeability reservoir

A polyelectrolyte complex solution for water control in the hydraulic fracturing of low permeability reservoir was prepared via solution blending of anionic polyacrylamide(HPAM) and cationic polymers(DP-1).The stable conditions of anionic polymers and cationic polymers were studied.The heat resistance,salt tolerance,anti-shearing,flushing resistant and water control performance of polyelectrolyte complex solution were evaluated,respectively.The results showed that anionic polymers and cationic polymers can form a stable polyelectrolyte complex solution with low viscosity adding a certain amount of salt(KCl),the complex solution possessed the good heat resistance and salt tolerance;the viscosity of complex solution declined at initial stage and then increased with the increasing of shear rate;in core flooding testing at 60 ℃,the residual resistance factor of the complex solution was 2.66 after the 100 PV saline displacement.At the same time,the water permeability can be reduced by 90.53% and oil permeability was decreased slightly about 14.60%.This reflected the significant characteristic of disproportionate permeability reduction of the polyelectrolyte complex solution.The complex solution can be used as additives for water control in the fracturing treatment of low permeability reservoirs near water formation or in high water-cut formation in order to reduce the in-situ treatment risk.